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Aug. 28, 1928. 1,682,199

R. H. SMILIE TENNIS RACKET Filed Dec. 17 19 7 :E lml,

INVENTOR Robe/'2" H. 501/71? Patented 28, 1928.

ROBERT H. SMILIE, .OF OAKLAND. CALIFORNIA.

TENNIS BLACKET.

Application filed December 17, 1927. Serial No. 240.722.

Myinvention relates to improvements in tennis rackets. The game oftennis is found.

to be a rather expensive game, for one reason due to the rapid wearingoutof the strings of the rackets used. On the close observation under amicroscope of the playing surface'of a racket I have discovered thatinvariably the strings break down at their intersections or crossings.This of course may be eX- plained as caused by the frictional engagementbetween the strings for although a racketmay be very tightly strungthere is always a more orless lateral motion of each-string with respectto the strings with-which it is interlaced. Each impact bet-ween theball and the racket causes the strings of the intersections so broughtinto play, to be pressed together andso bruise and permanently injuretheir contacting surfaces. My observation: also disclosed the factthaton an impactibet-ween a ball and racket, at most four strin areactually brought into contact with the ball. and due to the fact thatthe coeflicient of friction ofv string on string is insufficient toprevent the lateral motion of one string with respect to itsintersecting string, the load placed on the racket by the-impinge mentwith the ball is earriedlargely bythe fourstrings so brought intocontact.

In general it is the object of my invention to provide an insulatingmeans between the intersecting strings of a racket and thereby toprevent the frictional engagementof such intersecting strings andconsequently to prevent their bruising and wearing.

.Another object of my invention is the provision of means whereby theload placed on a racket by its impingement with a ball, will be more orless evenly distributed on all of 'its strings thereby eliminating anyundue strains from being placed on any one string.

.Another object of my invention is the provision of a flexible. doubleconcaved disc to be interposed between intersecting strings of a racketand in which the intersecting portions of said strings may be embeddedand embraced thereby.

Another object of my invention is the provisions of an insulating discadapted to be interposed between the intersections of the strings of aracket. and which is made of a material. the coefficient of friction ofwhich on the strings of a racket is greater than the coefiicient offriction between string on string. and which will therefore prevent thestrings from creeping.

My invent-ion possesses other advantageous features, some of which withthe foregoing will be set forth at'length in the following descriptionwherelI shallou'tline in fullf'that form of the tennis racket ofmyinven'tion which I have selected for illustration-in the drawingsaccompanying and ."forming part of the present specification. -AilthoughI have shown in the drawingsbut oneform-of my invention, I do not desire"to 'be'limited thereto, since the invention as definedin the.

claims .may'be embodied in other "forms. also.

Referring to the drawings: .Fig. 1 is an elevational view of a tennisracket embodying the use ofiny invention.

Fig. 2 is aplanview ofmylfiexiblmdorible concaved insulating disc. 7Flg. 3 1s a mid-section.of-lthelinsulating dlsc shownin Fig. .2.

-5Fig. 4 isa sectional view takenrparallelto one set of intersecting:strings of araket showing thermanner .in which. insulating discs areinterposedlbetween .the intersections of a string.

Fig. 5 is a mid-sectional view of' areenforcedinsulating disc.

lFig. '6-is aperspective viewof la sstring tersection showing themannenin which: such intersecting strings are :enibedded and .embraced inaninterposedinsulating disc.

In accordance with myinventionrmy im sulating disc .1 .is preferablymoldedofrubher or other.iiexiblematerial. Eahfface of my insulatingdiscf is dished or "concave ..as at .2 and 3. In.aetual practicelhave.made these discs of a diameter approximately. equal tothreediametersofthewstrings.on a racket butthey may :ofcours'e'be madeofany other suitable .size. These Iins ilating discs are then interposedbetween. intersections of the stringsof'..apracket-and whenrsointerposed .are found tox assume .the formation as best shown in Figs. 4and 6. Referring particularly to 6. the string 4: of a pair ofintersecting strings 4 and 5 is embedded within the upper surface of oneof my insulating discs while the string 5 is embedded in its lowersurface. It will be noted that the string 4 engages with the peripheralportions 6 and 7 to cause these peripheral portions to embrace thestring 5 and that the string 5 engages the peripheral portions 8 and 9so as to cause these peripheral portions to embrace string 4. Thematerial. of which these insulating discs are made is so chosen that itscoefliecient of the friction on the strings is substantially greaterthan the coeflicient of friction between a string on a string. By havingsuch an increased coeflicient of friction and due to the manner in whichthe intersecting strings are embedded and embraced within the insulatingdiscs the strings are prevented from creeping or moving laterally oneach other thereby decreasing the frictional wear of the strings.

It has been found that the resiliency of a racket constructed inaccordance with my invention is greatly increased thereby producing afaster racket. To further increase the resiliency of the racket and toincrease the durability of my insulating discs I have found itpreferable to reenforce the insulating disc by means of a centrallydisposed fibrous disc 11 as shown in Fig. 5. This fiber reenforcing-1nember is embedded in and made integral with the insulating disc. Inthis form of insulating'disc it is'to be noted that at its center itsthickness is substantially that of the fiber reenforcing member. Whensuch an insulating disc is interposed between intersecting strings, thefiber 11 is practically all that separates the strings and being harderV and more resilient than its surrounding rubber, responds somewhatfaster to the action of the strings than an unreenforced disc. The fiberreenforcing member also increases the durability and life of theinsulating disc, their life being about equal to the life of thestrings. I Y

' The use of such insulating discs also has the effect of producing agreater and more even frictional surface between the racket and the ballthereby permitting a greater accuracy when it is desired to give apredetermined spin to the ball.

Although I have found it preferable to construct such an insulating discof a flexible material, I have constructed some of aluminum. When somade they are molded to the form show in Fig. 6 and are provided withwedge shaped grooves for gripping the strings. These metallic devicesserve to insulate or separate the intersecting strings but it has beenfound that their gripping action on the strings isnot as great as thatof the rubber insulation.

, By preventing the lateral motion or creeping of the strings withrespect to each other it can be seen that when there is an impmgementbetween a ball and the racket the load thereby placed on the racket,will be carried not only by the four strings with which the ballactually engages, but will be distributed to a plurality of stringsadjacent these four strings. This of course decreases the chances of aworn or defective string from breaking due to carrying too great aportion of the total load and also insures a uniform playing surface atall times.

By the above disclosure it can be seen that I have not only provided ameans whereby the life of the strings of a tennis racket is greatlyincreased but by the use of such means the playing qualities of a racketare also improved, that is, the racket is faster and enables the playerto control more accurately the motion of the ball. Actually the life ofthe strings has been found to be doubled or tripled and that for a givenamount of energy, the rebound of a ball when my improved racket is used,is much greater than with the rackets now in use.

I claim: I

l. A racket comprising aframe, a plurality of interlaced stringssupported by said frame and a plurality of deformed double concave discsinterposed between said strings.

2. As a new article of manufacture a disc of flexible material providedwith a central reinforcing member and adapted to insulate the strings ofa reticulated material.

3. As a new article of manufacture, a flexible double concave discadapted to insulate the strings of a racket.

4. A tennis racket comprising a frame, a plurality of intersectingstrings supported by said frame and a plurality of flexible centrallyreinforced discs interposed between said strings.

5. A tennis racket comprising a frame, a plurality of intersectingstrings supported by said frame and a plurality of flexible, doubleconcave discs interposed between said strings.

In testimony whereof, I have hereunto set my hand.

ROBERT H. SMILIE.

